onHealthCheck not available in apollo-server-express

[david-wb]

The title says it all. ApolloServerExpressConfig does not have an onHealthCheck property while the standalone config does. This is a bug right? I'm using apollo-server-express version 2.22.2.

Thanks

[glasser]

onHealthCheck is an argument to applyMiddleware in apollo-server-express rather than the constructor. (It's in the constructor for apollo-server because that package takes care of the equivalent of applyMiddleware for you.)

This is not particularly documented well. In fact in general, we do a bad job of documenting all of the different package APIs fully accurately (despite the fact that, about the same number of projects use apollo-server-express directly as use apollo-server). I'm hoping to overhaul our docs as part of our current work on Apollo Server 3; see #5097